This invention relates to an improvement to a clutch for preventing reverse rotation in scroll compressors that prevents the clutch from engaging when powered reverse rotation occurs.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor, a pair of scroll members each have a base and a generally spiral wrap extending from the base. The spiral wraps interfit to define compression chambers. One of the two scroll members is caused to orbit relative to the other, and as the two orbit compression chambers defined between the interfitting scroll wraps decrease in volume, compressing a refrigerant.
One problem with scroll compressors is that they are designed to orbit in a single direction. If for some reason the scroll member orbits in a reverse direction, the results are undesirable.
Reverse rotation can occur in one of two ways. First, unpowered reverse rotation can occur at shutdown of the compressor. At some point, the force from the entrapped refrigerant can cause the orbiting scroll to be driven in the reverse direction. This is generally a short transient phenomena, and results in undesirable noise.
Another type of reverse rotation is powered reverse rotation. This type of reverse rotation generally occurs when a motor for driving the orbiting scroll is miswired. Powered reverse rotation can occur for longer periods of time, and will often result in damage to the compressor.
One proposed solution to reverse rotation is the use of a one-way clutch within the scroll compressor. In one type of clutch, the compressor is provided with a clutch member that is normally in a first position where it does not affect transmission of orbiting movement to the orbiting scroll, nor does it affect the scroll wraps being kept in engagement with each other sealing and defining compression chambers. In this known clutch, if reverse rotation occurs, the clutch member will rotate, and surfaces will lock and engage surfaces within the drive housing, creating a breaking action. This will slow or halt the reverse rotation, and will reduce the undesirable noise mentioned above.
One such proposed clutch is shown in U.S. Pat. No. 5,545,019. This clutch is beneficial for stopping unpowered reverse rotation. However, there has sometimes been problems with these systems during powered reverse rotation. In particular, during powered reverse rotation, the clutch members have sometimes been destroyed.
The present invention is thus directed to protecting clutches during powered reverse rotation. While the invention is disclosed with a clutch as in the above patent, other clutches may benefit.
In a disclosed embodiment of this invention, an eccentric pin on a driveshaft is received within a slider block for the orbiting scroll, as known. As farther generally known, the slider block and eccentric pin are structured such that during forward rotation flat surfaces on the eccentric pin engage the flat surfaces on the slider block to drive the orbiting scroll and also hold the orbiting scroll wrap against the non-orbiting scroll wrap.
However, should powered reverse rotation occur, a surface on the eccentric pin will engage a surface on the slider block, and cause the slider block to move out of position. The slider block will then engage a lug on an inner periphery of the clutch. With the slider block engaging the lug, the clutch will not be allowed to rotate to its engaged position. This movement of the slider block will not occur during unpowered reverse rotation.
In this way, the clutch will brake the shaft during non-powered reverse rotation, but the inventive structure prevents the clutch from engaging during non-powered reverse rotation. Thus, the clutch will be protected.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.